When remembering jobs in the basket, they can be stored in two ways. First is in a cookie, second is by applicants user credentials in the database. The first approach has to be used when handling a non-logged in user with a client access token. The second approach should be used when having a logged in user with a user access token. Then you just leave out the cookie parameter, it is ignored anyway.
When restoring the job basket, there are again the two scenarios with client and user access tokens. Use the cookie parameter, when having a client access token. With the user access token there are two approaches. The user could have added jobs to the basket before logging in. When you want to merge that content to his basket as a logged in user, then keep the cookie parameter in the API call. When leave it out, only jobs added to the basket when he was logged in, will be fetched.